Ophiosparte Koehler, 1922

Martynov, Alexander, 2010, Reassessment of the classification of the Ophiuroidea (Echinodermata), based on morphological characters. I. General character evaluation and delineation of the families Ophiomyxidae and Ophiacanthidae 2697, Zootaxa 2697, pp. 1-154 : 96-97

Genus Ophiosparte Koehler, 1922

Figure 65

Ophiosparte Koehler, 1922b: 21

Type and single species: Ophiosparte gigas Koehler, 1922 , by monotypy Diagnosis. The disk scales are obscured by a strong skin layer. The radial shields are large, largely concealed by skin. The genital plates are well developed. The strong adradial genital plate is almost straight and has a well-defined articulation surface with a short lateral ridge. The abradial genital plate articulates with the adradial genital plate at the level of the articulation surface and is broad, flattened. The genital slits are long and genital plates line almost the entire length of the slits. There are arm comb papillae on the genital plates. The jaw bears numerous spiniform oral papillae similar in shape to the large cluster of the ventralmost teeth. Oral papillae, teeth and spines have a specific shape, widened apically. Three pairs of the adoral shield and adjacent oral papillae are placed around the tentacle scale, similar in shape to the teeth and lateral arm spines. The teeth are spiniform. All teeth are of similar shape. The dental plate possesses numerous irregularly placed rounded sockets, with several strong folds in-between. The oral shield is strongly convex distally, sometimes with a weak lobe, and slightly triangular proximally. The adoral shields are obscured by skin, both ends are of similar size. The dorsal and ventral arm plates are well developed. The dorsal arm plates are oval, with straight edges both distally and proximally, contiguous, unfragmented even proximally. The arm spine articulations possess a large rounded muscle opening bordered by a low elevation, and, at considerable distance from it, a small nerve opening. Correspondingly, the basal part of the spine has a nerve opening not strictly ventrally, but laterally. The ventral arm plates are contiguous, with convex distal and straight proximal edge. The arm spines are long, solid, widened apically, not hooked distally. Several tentacle scales, similar in shape and size to the spines, are placed on the lateral arm plate. The vertebrae have a well-defined median keel and are blunt distally. The articulation is a special variant of the zygospondylous type, known as the “comb-shaped” type (see Litvinova, 1989a, b). The podial basins are moderate in size.

Material studied. MCZ 6805 (27081), 1 specimen ; ZIN 25 /21449, 1 specimen ( Fig. 65) ; MNHN, EcOs 10761, 1 specimen .

Remarks. Ophiosparte gigas is a well-known Antarctic taxon, inhabiting the shelf zone. However its exact systematic position is still unresolved. Until recently its initial taxonomic placement within the family Ophiacanthidae ( Koehler 1922b) was challenged only in a single study ( Dearborn et al. 1996), who suggested an ophiomyxid relationship. Paterson (1985) included Ophiosparte in the ophiacanthid subfamily Ophiotominae , and therefore it bears a special interest for the present study. The type material of Ophiosparte gigas is in the Australian Museum ( Rowe, Pawson, 1977).